During the manufacture of Thin Film Transistor Liquid Crystal Display, an alignment film (i.e., a polyimide film after orientation) is typically used such that the crystal molecules are uniformly aligned on the surface of the film, to achieve an oriented arrangement of the liquid crystal molecules. Because the light will be partially absorbed by the polyimide film when it passes the film, a polyimide film having high transmittance plays a critical role in the manufacture of a liquid crystal display panel having low energy consume and high contrast.
A conventional polyimide film is shown below:

wherein, Ar may be phenyl, naphthyl, diphenyl ketone group, diphenylmethane group, diphenylether group, or diphenyl sulfonyl. Such conventional polyimide typically has a light transmittance of about 70-75%.